Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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876 FXUS62 KRAH 091849 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 250 PM EDT Thu May 9 2024 .SYNOPSIS... A series of upper level disturbances will interact with an unseasonably moist airmass over North Carolina through Friday, bringing unsettled weather. A cold front will move across the region late Friday, ushering in drier and less humid air for the weekend. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 250 PM Thursday... The risk of any storms, much less severe storms, is very much in doubt for the rest of today, given a considerable amount of SBCINH resulting from the stabilization effects of earlier rain and outflows along with low-mid level W and WNW flow components. While the overcast low deck over much of the Piedmont earlier today has mixed out and lifted, a few low clouds still linger across the area, topped by anvil cirrus as the most robust and organized convection continues to propagate ESE over S GA and S/E SC. However, the existing CINH has shown a waning trend in recent hours with the increasing filtered sunshine this afternoon, and the deep layer bulk shear has rebounded to over 35-40 kts as well, leaving us with marginal CAPE and sufficient mid level flow to support isolated storms. While the most prominent mid level perturbation will be pushing E of the area in the next few hours, we`ll still need to watch our northern sections for a few isolated showers or storms as CINH there is expected to vanish briefly through early evening with 1000-1500 J/kg SBCAPE, and we`re already seeing some agitated cu over and north of the Triad. Other than this isolated convection threat over the next few hours, we should see dry weather from this evening through the overnight hours as PW aob 1" spreads in from the west, with diminishing CAPE and flow becoming deeply W to WNW aloft. Will trend remaining low pops down and out by sundown, with skies fair to partly cloudy overnight. After rather seasonable readings today peaking in the upper 70s to lower 80s, expect lows tonight in the 60s. -GIH && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 300 AM Thursday... A positively-tilted shortwave trough will approach from the TN Valley on Friday, becoming more neutrally-tilted as it crosses central NC on Friday evening. An MCS will also be moving east across GA and SC early in the day, and while the exact location it will be is still unclear, most high-res guidance keeps it to our south as it exits into the Atlantic. At the surface, a cold front will begin to cross through central NC as a wave of low pressure rides along it, but exactly how far south and east it gets is a bit uncertain. The aforementioned shortwave will provide some upper forcing for ascent, so scattered showers will be possible anywhere on Friday afternoon and evening, but the main threat of storms will be along and ahead of where the front sets up. The 00z HREF has CAPE values around 500- 1000 J/kg across our southernmost tier of counties, which is where the SPC expanded a marginal (level 1 of 5) risk of severe storms. Damaging straight-line winds and hail are the main threats. Instability and moisture will not be as high as today or yesterday even down there, so convective coverage doesn`t appear great enough to justify likely POPs anywhere, but they are still around 50% in the far south. Forecast highs range from mid-70s far north to lower- 80s far south. Any precipitation will come to an end Friday night as the cold front sweeps off the coast and lows turn slightly below normal (upper-40s to mid-50s). && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 211 PM Thursday... In the wake of the departing upper trough Friday night, NW flow will take hold across the area on Saturday. This will allow for continued dry advection and noticeably cooler temperatures, as highs will only reach the low to mid 70s across the area. A weak shortwave trough is expected to rotate through southern VA/northern NC late in the day Saturday which will bring about a brief increase in cloud cover and perhaps a stray shower or two, but that`s about it. Model guidance has been consistent in showing limited precip across the area thanks in large part to a dry BL featuring dewpoints in the 40s. PoPs in the 15-20 percent range across the northern tier of counties still seems appropriate based on today`s ensemble guidance (but even this may be overdone a bit). Any showers that do manage to make it into the forecast area should dissipate quickly after sunset with dry weather expected Saturday night. Lows will range from the upper 40s to lower 50s. Sunday will see mostly sunny skies and continued cool/dry conditions as weak cyclonic flow aloft gradually flattens out as a ridge builds to our west. Look for another day of below normal highs (mid 70s) with low temps once again falling into the upper 40s to low 50s. No concerns about precip as all forcing will be displaced well to the northeast of the area. The overall pattern next week looks to be active once again. An upper low over the Central Plains will slowly migrate eastward on Monday, inducing downstream ridging across the Southeast states and ultimately resulting in a fairly quiet day across NC with near normal temps and dry weather. This will ultimately change though as the low migrates into the Ohio Valley on Tuesday. Broad/weak forcing for ascent will overspread much of the Southeast on Tuesday coincident with an increase in moisture transport (PW`s will be back above 1.5 inches by Tuesday morning). Showers are expected across the area on Tuesday although just how quickly they arrive is still a little unclear (daybreak Tuesday vs afternoon). Regardless, Tuesday is likely to see widespread cloud cover and rainfall with cooler temps as a result. While thunder seems unlikely at this stage (instability displaced well to the south), precip chances will likely be maximized during the daytime hours with lesser chances Tuesday night into Wednesday morning. Wednesday will see continued precip chances as the upper low opens up and moves through the central Mid Atlantic. As PW`s will remain elevated and the area will be well within the warm sector, instability will be much more readily available on Wednesday ahead of the trough and shower/thunderstorm chances should be a bit higher (60-70 percent range) especially during the afternoon hours. It`s also likely that we`ll have at least some clearing to start the day and temps should make it up into the low/mid 80s prior to the arrival of the trough. Thursday should start off dry in the wake of the departing low, but this looks to be short lived. While shortwave ridging aloft will build in early in the day, this will quickly turn southwesterly as yet another longwave trough sets up across the Central Plains and kicks out a series of embedded shortwaves across the Southeast states through the end of the week. This would favor diurnally driven showers and thunderstorms Thursday afternoon/evening, followed by drying overnight. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 140 PM Thursday... The coverage of showers and storms has trended much lower than what we expected earlier, as the stronger storms have held south of the NC/SC border, leaving central NC with just isolated showers at most. Earlier IFR to MVFR cigs over the Piedmont terminals (INT/GSO/RDU) has lifted and mixed to scattered, and we should see scattered 2- 3kft clouds plus a mix of scattered higher base cu with patchy mid and high level clouds for the next 24 hours. Another round of scattered showers and storms is expected across the S and SE Fri, but this risk will be limited to near FAY and most likely after the end of the TAF valid period. Surface winds will be around 10 kts or less from the SW through tonight and from the W Fri, with a few gusts to 15-20 kts possible this afternoon. Looking beyond 18z Fri, S and E sections including FAY may see a storm pass nearby during the mid to late afternoon Fri. Otherwise, VFR conditions are expected through at least Mon, with a cooler and less humid air mass moving in starting late Fri. Rain and isolated storms are expected to move in Tue morning, with an increasing chance of sub-VFR conditions. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Danco LONG TERM...Leins AVIATION...Hartfield